PPC: Fix return register number for unwinding

Change-Id: I6586dc2b681b93cb5401b3e990786ee407baff73
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2012520Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
Commit-Queue: Milad Farazmand <miladfar@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#65897}

src/compiler/backend/ppc/unwinding-info-writer-ppc.cc

@@ -89,7 +89,7 @@ void UnwindingInfoWriter::MarkLinkRegisterOnTopOfStack(int pc_offset) {
 
   eh_frame_writer_.AdvanceLocation(pc_offset);
   eh_frame_writer_.SetBaseAddressRegisterAndOffset(sp, 0);
-  eh_frame_writer_.RecordRegisterSavedToStack(r30, 0);
+  eh_frame_writer_.RecordRegisterSavedToStack(kLrDwarfCode, 0);
 }
 
 void UnwindingInfoWriter::MarkPopLinkRegisterFromTopOfStack(int pc_offset) {